Thick inner cover multi-layer golf ball

ABSTRACT

A golf ball includes a core having a center and an outer core layer formed from a polyoctenamer. The core has a compression of 70 or less, an outer diameter of 1.38 to 1.387 inches, and a COR of 0.770 to 0.810. An intermediate layer is formed over the core, the intermediate layer having a thickness of 0.015 to 0.07 inches, a hardness of 55 to 70 Shore D, and including a highly-neutralized ionomer. A cover including an inner cover layer and an outer cover layer is formed over the intermediate layer. The outer cover layer has a thickness of 0.02 to 0.04 inches and includes a castable polyurethane having a hardness of 40 to 60 Shore D. A combination of the core and the intermediate layer has a compression of 60 or greater and the golf ball has a COR of 0.805 or greater.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of co-pending U.S. patent applicationSer. No. 12/102,092, which is a continuation of U.S. patent applicationSer. No. 11/469,049, filed Aug. 31, 2006 and now U.S. Pat. No.7,357,734, which is a continuation of U.S. patent application Ser. No.11/267,487, filed Nov. 4, 2005 and now U.S. Pat. No. 7,150,687, which isa continuation of U.S. patent application Ser. No. 10/841,031, filed May7, 2004 and now U.S. Pat. No. 7,004,856, the disclosures of which areincorporated herein by reference.

FIELD OF THE INVENTION

This invention generally relates to golf balls with high coefficient ofrestitution and low deformation, and more particularly to also a highcoefficient of restitution golf ball at high club speeds.

BACKGROUND OF THE INVENTION

Golf balls have been designed to provide particular playingcharacteristics. These characteristics generally include initial ballvelocity, coefficient of restitution (COR), compression, weightdistribution and spin of the golf ball, which can be optimized forvarious types of players.

Golf balls can generally be divided into two classes: solid and wound.Solid golf balls include single-layer, dual-layer (i.e., solid core anda cover), and multi-layer (i.e., solid core of one or more layers and/ora cover of one or more layers) golf balls. Wound golf balls typicallyinclude a solid, hollow, or fluid-filled center, surrounded by tensionedelastomeric thread, and a cover.

Generally, the hardness of a golf ball or a golf ball core is one amongother factors used in designing golf balls. Typically, when a ball ishard, e.g., possessing high compression values and low deformation whenstruck by a club, it typically has high COR and high initial velocityafter impact with a golf club. However, hard ball has a “hard” feel andis difficult to control around the greens. A softer ball, e.g., lowercompression value and high deformation, has a “soft” feel and is easierto control with short iron clubs for greenside play. Recently developedsolid balls have a core, at least one intermediate layer, and a cover.The intermediate layer improves other playing characteristics of solidballs, and can be made from thermoset or thermoplastic materials.

Recent advancements in golf ball design can produce golf balls with lowcompression for soft “feel” and high COR for long flight distance. TheCOR for low compression balls, however, decreases at higher impact speedwith golf clubs.

Hence, there remains a need in the art for low compression golf ballsthat have high coefficient of restitution at low impact speeds and athigh impact speeds.

SUMMARY OF THE INVENTION

The present invention is directed to a golf ball comprising a corecomprising a halogenated thiophenol and having a diameter of from about1.3 inches to about 1.4 inches, a compression of about 44 or less; and acoefficient of restitution of from about 0.770 to about 0.810; a castpolyurethane or polyurea cover; and an intermediate layer disposedbetween the core and the cover, the intermediate layer having athickness of from about 0.11 inches to about 0.12 inches and beingformed from a composition comprising at least two ionomers; wherein acombination of the core and the intermediate layer results in acompression of from about 70 to about 100, and the golf ball has acoefficient of restitution of from about 0.805 to about 0.820 at about125 ft/s and a compression of from about 75 to about 105.

The core typically has a diameter of from about 1.380 inches to about1.387 inches and/or a coefficient of restitution of from about 0.774 toabout 0.805. The intermediate layer thickness may also be from about0.115 inches to about 0.119 inches, and the intermediate layer hardnessmay be from about 55 Shore D to about 70 Shore D. In one embodiment, thecombination of the intermediate layer and the core has a coefficient ofrestitution of from about 0.810 to about 0.820. In another embodiment,the combination of the intermediate layer and the core has a compressionof from about 72 to about 90.

The cover may be a castable polyurethane or polyurea material, andpreferably has a hardness of from about 40 Shore D to about 60 Shore D.The halogenated thiophenol in the core is typically present in an amountof from about 0.01 pph to about 5 pph. The at least two ionomers arepartially- or fully- (10-100%) neutralized by a metal cation, such asNa; Zn; Mg; Li; Ca; Ba; Pb; Al; and K metal cations.

The present invention is further directed to a golf ball comprising acore comprising a halogenated thiophenol, and having a diameter of about1.4 inches or less, a compression of about 70 or less; and a coefficientof restitution of from about 0.770 to about 0.810; a cover; and anintermediate layer disposed between the core and the cover, theintermediate layer having a thickness of from about 0.1 inches to about0.5 inches and being formed from a composition comprising at least twoionomers; wherein a combination of the core and the intermediate layerresults in a compression of about 60 or greater, and the golf ball has acoefficient of restitution of about 0.800 or greater at about 125 ft/sand a compression of from about 85 to about 105.

The cover may include partially- or fully-neutralized ionomers,metallocene-catalyzed polymers, single-site catalyzed polymers,polyesters, polyethers, balata, crosslinked diene rubbers, styrene blockcopolymers, polyurethanes, polyureas, polyurethane-ureas,polyurea-urethanes, or non-ionic fluoropolymers.

The intermediate layer preferably has a flexural modulus of about 50,000psi or greater and/or a hardness of about 55 Shore D or greater. Thecore diameter is preferably from about 1.375 inches to about 1.40inches. The at least two ionomers are typically neutralized by a metalcation, such as Na; Zn; Mg; Li; Ca; Ba; Pb; Al; and K metal cations.

The present invention is also directed to a golf ball comprising a corehaving a compression of about 50 or less and a coefficient ofrestitution of about 0.800 or greater; a cover; and an intermediatelayer disposed between the core and the cover, the intermediate layerhaving a thickness of about 0.110 inches or greater; wherein acombination of the core and the intermediate layer results in acompression of about 60 or greater and a coefficient of restitution ofabout 0.805 or greater at about 125 ft/s.

The core preferably has a diameter of from about 0.5 inches to about 1.4inches and a compression of about 45 or less; and the intermediate layerhas a flexural modulus of from about 50,000 psi to about 150,000 psi anda thickness of about 0.12 inches or greater.

The cover may include a thermoset polymer having a hardness of about 64Shore D or less and has a thickness of from about 0.02 inches to about0.1 inches. The core can have a diameter of about 0.8 inches to about1.4 inches. In one embodiment, the core includes a center and at leastone outer core layer and/or the intermediate layer includes two or morelayers. Preferably, the core includes a halogenated thiophenol. The atleast two ionomers are generally neutralized by a metal cation, such asNa; Zn; Mg; Li; Ca; Ba; Pb; Al; and K metal cations.

The present invention is also directed to a golf ball comprising a corehaving a diameter of 0.5 inches to 1.4 inches, a compression of about 45or less, and a COR of 0.770 to 0.810; a cast polyurea cover; and anintermediate layer disposed between the core and the cover, theintermediate layer having a thickness of 0.11 inches or greater andbeing formed from a composition comprising a highly-neutralizedthermoplastic material comprising an ethylene, α,β-ethylenicallyunsaturated C₃₋₈ carboxylic acid copolymer(s), a fatty acid salt, and asufficient amount of a cation source to increase the level ofneutralization of all the acid moieties to 100%, wherein a combinationof the core and the intermediate layer results in a compression of 70 toabout 100, and the golf ball has a COR of 0.805 to 0.820 when measuredat an incoming velocity of 125 ft/s and greater than 0.75 when measuredat an incoming velocity of 160 ft/s, and a compression of from 75 to105.

The core typically has a diameter of 0.8 inches to 1.4 inches and theintermediate layer should have a flexural modulus of from 50,000 psi to150,000 psi and a thickness of 0.12 inches or greater. Preferably, thecore has a diameter of 1.3 inches to about 1.4 inches. The golf ball mayfurther include an inner cover layer located between the cover layer andthe intermediate layer. The intermediate layer thickness is typically0.115 inches to 0.119 inches and has a hardness of 55 Shore D to 70Shore D.

A sphere resulting from a combination of the intermediate layer and thecore generally has a COR of 0.810 to 0.820 when measured at an incomingvelocity of 125 ft/s and a compression of 72 to 90.

The thermoset polyurea cover has a hardness of 40 Shore D to 60 Shore D.In one embodiment, the core comprises a halogenated thiophenol.Preferably, the halogenated thiophenol is present in an amount of 0.01pph to 5 pph, more preferably 2.2 pph to 4 pph.

The present invention is further directed to a golf ball comprising acore having a compression of about 50 or less and a COR of 0.800 orgreater; a thermoset polyurea cover having a hardness of 64 Shore D orless and a thickness of 0.02 inches to 0.1 inches; and an intermediatelayer disposed between the core and the cover, the intermediate layerhaving a thickness of about 0.110 inches or greater; wherein at leastone of the core or intermediate layer comprise a composition comprisinga highly-neutralized thermoplastic material comprising an ethylene,α,β-ethylenically unsaturated C₃₋₈ carboxylic acid copolymer(s), a fattyacid salt, and a sufficient amount of a cation source to increase thelevel of neutralization of all the acid moieties to 100%; and wherein acombination of the core and the intermediate layer results in acompression of about 60 or greater and the golf ball has a COR of 0.805or greater when measured at an incoming velocity of 125 ft/s and greaterthan 0.75 when measured at an incoming velocity of 160 ft/s.

In one embodiment the core has a diameter of 0.5 inches to 1.4 inchesand, more preferably, 0.8 inches to 1.3 inches. The golf ball mayfurther include an inner cover layer located between the cover layer andthe intermediate layer. The intermediate layer generally has a hardnessof 55 Shore D to 70 Shore D whereas the thermoset polyurea covertypically has a hardness of 40 Shore D to 60 Shore D. A sphere resultingfrom a combination of the intermediate layer and the core has acompression of 70 to 100.

DEFINITIONS

The following terms that are used in this application are defined interms of the enumerated ASTM tests: Specific Gravity ASTM D-792,Flexural Modulus ASTM D-790, Shore D Hardness ASTM D-2240, and Shore CHardness ASTM D-2240. The ASTM D-792 test was carried out in labconditions where the temperature was controlled to 20-23° C.

As used herein, the terms “points” and “compression points” refer to thecompression scale or the compression scale based on the ATTI EngineeringCompression Tester. This scale, which is well known to those working inthis field, is used in determining the relative compression of a core orball. Compression is measured by applying a spring-loaded force to thegolf ball center, golf ball core or the golf ball to be examined, with amanual instrument (an “Atti gauge”) manufactured by the Atti EngineeringCompany of Union City, N.J. This machine, equipped with a Federal DialGauge, Model D81-C, employs a calibrated spring under a known load. Thesphere to be tested is forced a distance of 0.2 inches (5 mm) againstthis spring. If the spring, in turn, compresses 0.2 inches, thecompression is rated at 100; if the spring compresses 0.1 inches, thecompression value is rated as 0. Thus more compressible, softermaterials will have lower Atti gauge values than harder, lesscompressible materials. Compression measured with this instrument isalso referred to as PGA compression.

As used herein, “COR” refers to Coefficient of Restitution, which isobtained by dividing a ball's rebound velocity by its initial (i.e.,incoming) velocity. This test is performed by firing the samples out ofan air cannon at a vertical steel plate over a range of test velocities(from 75 to 150 ft/s). A golf ball having a high COR dissipates asmaller fraction of its total energy when colliding with the plate andrebounding therefrom than does a ball with a lower COR. Unless otherwisenoted, the COR values reported herein are the values determined at anincoming velocity of 125 ft/s.

As used herein, the term “copolymer” refers to a polymer which is formedfrom two or more monomers, wherein the monomers are not identical.

As used herein, the term “terpolymer” refers to a polymer which isformed from three monomers, wherein the monomers are not identical.

As used herein, the term “fillers” includes any compound or compositionthat can be used to vary the density and other properties of the subjectgolf ball cores.

As used herein, the term “pph” in connection with a batch formulationrefers parts by weight of the constituent per hundred parts of the basecomposition (e.g., elastomer).

As used herein, the term “Mooney viscosity” refers to the unit used tomeasure the plasticity of raw or unvulcanized rubber. The plasticity ina Mooney unit is equal to the torque, measured on an arbitrary scale, ona disk in a vessel that contains rubber at a temperature of 100° C. androtates at two revolutions per minute. The measurement of Mooneyviscosity is defined according to ASTM D-1646.

The term “about,” as used herein in connection with one or more numbersor numerical ranges, should be understood to refer to all such numbers,including all numbers in a range.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The golf balls of the present invention may comprise any of a variety ofconstructions, such as a two-piece, three-piece, multi-layer, or woundball having a variety of cores, intermediate layers, covers, andcoatings. The covers and cores of the present invention includestructures comprising one or more layers. Cores may include a single,unitary layer, comprising the entire core from the center of the core toits outer periphery, or may contain a center surrounded by at least oneouter core layer. The center, the innermost portion of the core, ispreferably solid, but may be hollow or liquid-, gel-, or gas-filled. Theouter core layer may also be a wound layer formed of a tensionedelastomeric material. Cover layers of the present invention may alsocontain one or more layers, such as a double cover comprising an innerand outer cover layer. Optionally, an intermediate layer disposedbetween the core and cover may be incorporated. The intermediate layer,if present, may comprise one or more layers, and are sometimes referredto in the art, and, thus, herein as well, as inner cover layers, outercore layers, or mantle layers.

In accordance to the present invention, a golf ball is provided with alow compression and high COR layer, which is supported or otherwisereinforced by a low deformation layer. Preferably, the low compression,high COR layer is made from a polymer composition including ahalogenated thiophenol compound. Such rubber and halogenated thiophenolcomposition is fully disclosed in U.S. Pat. No. 6,635,716, thedisclosure of which is hereby incorporated by reference in its entirety.

The preferred polymeric composition comprises a base rubber compound, aco-reaction agent, a filler, a halogenated thiophenol compound and aco-crosslinking or initiator agent. The base rubber compound typicallyincludes natural or synthetic rubbers. A preferred base rubber is1,4-polybutadiene having a cis-structure of at least 40%, morepreferably at least about 90%, and most preferably at least about 95%.Most preferably, the base rubber comprises high-Mooney-viscosity rubber.Preferably, the base rubber has a Mooney viscosity greater than about35, more preferably greater than about 50. Preferably, the polybutadienerubber has a molecular weight greater than about 400,000 and apolydispersity of no greater than about 2. A common indicator of thedegree of molecular weight distribution of a polymer is itspolydispersity, defined as the ratio of weight average molecular weight,M_(w), to number average molecular weight, M_(n). Polydispersity(“dispersity”) also provides an indication of the extent to which thepolymer chains share the same degree of polymerization. If thepolydispersity is 1.0, then all polymer chains must have the same degreeof polymerization. Since M_(w) is always equal to or greater than M_(n),polydispersity, by definition, is equal to or greater than 1.0. Suchrubber compounds are commercially available from Bayer of Akron, Ohio,UBE Industries of Tokyo, Japan, and Shell of Houston, Tex., amongothers. The base rubber may also be mixed with other elastomers known inthe art such as natural rubber, polyisoprene rubber and/orstyrene-butadiene rubber in order to modify the properties of the core.

Suitable co-reaction agents include a metal salt of diacrylate,dimethacrylate or monomethacrylate. Preferably, the co-reaction agent iszinc diacrylate (ZDA) and is present in the amount from about 5 to about40 and more preferably from about 5 to about 30 and most preferably fromabout 10 to about 20 parts per one-hundred parts of rubber compound(phr). Suitable cross-linking agents include any known polymerizationinitiator, which decomposes during the cure cycle. Such initiatorsinclude, but are not limited to, organic peroxide compounds such asdicumyl peroxide. In its pure form, the preferred amount of peroxide isbetween about 0.25 phr and about 2.5 phr. Any filler can be used in anydesired quantity to alter a property of the core, including specificweight, flexural modulus, moment of inertia, rheological properties,among others. Suitable fillers include, but are not limited to,tungsten, zinc oxide, barium sulfate, silica, metal oxides, ceramic andfibers.

Preferably, polybutadiene rubber compositions of the present inventioncontain halogenated thiophenol compound, more preferably about 0.01 pphto about 5 pph, and most preferably between about 2.2 pph and about 4pph. The halogenated thiophenol compound may includepentafluorothiophenol; 2-fluorothiophenol; 3-fluorothiophenol;4-fluorothiophenol; 2,3-fluorothiophenol; 2,4-fluorothiophenol;3,4-fluorothiophenol; 3,5-fluorothiophenol 2,3,4-fluorothiophenol;3,4,5-fluorothiophenol; 2,3,4,5-tetrafluorothiophenol;2,3,5,6-tetrafluorothiophenol; 4-chlorotetrafluorothiophenol;pentachlorothiophenol; 2-chlorothiophenol; 3-chlorothiophenol;4-chlorothiophenol; 2,3-chlorothiophenol; 2,4-chlorothiophenol;3,4-chlorothiophenol; 3,5-chlorothiophenol; 2,3,4-chlorothiophenol;3,4,5-chlorothiophenol; 2,3,4,5-tetrachlorothiophenol;2,3,5,6-tetrachlorothiophenol; pentabromothiophenol; 2-bromothiophenol;3-bromothiophenol; 4-bromothiophenol; 2,3-bromothiophenol;2,4-bromothiophenol; 3,4-bromothiophenol; 3,5-bromothiophenol;2,3,4-bromothiophenol; 3,4,5-bromothiophenol;2,3,4,5-tetrabromothiophenol; 2,3,5,6-tetrabromothiophenol;pentaiodothiophenol; 2-iodothiophenol; 3-iodothiophenol;4-iodothiophenol; 2,3-iodothiophenol; 2,4-iodothiophenol;3,4-iodothiophenol; 3,5-iodothiophenol; 2,3,4-iodothiophenol;3,4,5-iodothiophenol; 2,3,4,5-tetraiodothiophenol;2,3,5,6-tetraiodothiophenoland; and their zinc salts, the metal saltsthereof, and mixtures thereof. Preferably, the preferred halogenatedthiophenol is pentachlorothiophenol or a metal salt thereof. The metalsalt may be zinc, calcium, potassium, magnesium, sodium, and lithium,but is preferably zinc. Pentachlorothiophenol is commercially availablefrom Strucktol Company of Stow, Ohio, and zinc pentachlorothiophenol iscommercially available from eChinachem of San Francisco, Calif.

This preferred polybutadiene rubber composition may further include anα,β-unsaturated carboxylic acid or a metal salt thereof, an organicperoxide, and a filler. Also, as discussed in co-pending '448 patentapplication, another preferred polybutadiene rubber compound comprisingthe halogenated thiophenol compound is a mid Mooney viscositypolybutadiene having viscosity in the range of about 40 Mooney to about60 Mooney.

U.S. application Ser. No. 10/230,015, now U.S. Publication No.2003/0114565, and U.S. application Ser. No. 10/108,793, now U.S.Publication No. 2003/0050373, which are incorporated by reference hereinin their entirety, discuss soft, highly resilient ionomers, which arepreferably from neutralizing the acid copolymer(s) of at least one E/X/Ycopolymer, where E is ethylene, X is the α,β-ethylenically unsaturatedcarboxylic acid, and Y is a softening co-monomer. X is preferablypresent in 2-30 (preferably 4-20, most preferably 5-15) wt. % of thepolymer, and Y is preferably present in 17-40 (preferably 20-40, andmore preferably 24-35) wt. % of the polymer. Preferably, the melt index(MI) of the base resin is at least 20, or at least 40, more preferably,at least 75 and most preferably at least 150. Particular soft, resilientionomers included in this invention are partially neutralizedethylene/(meth) acrylic acid/butyl (meth)acrylate copolymers having anMI and level of neutralization that results in a melt processablepolymer that has useful physical properties. The copolymers are at leastpartially neutralized. Preferably at least 40, or, more preferably atleast 55, even more preferably about 70, and most preferably about 80 ofthe acid moiety of the acid copolymer is neutralized by one or morealkali metal, transition metal, or alkaline earth metal cations. Cationsuseful in making the ionomers of this invention comprise lithium,sodium, potassium, magnesium, calcium, barium, or zinc, or a combinationof such cations.

The invention also relates to a “modified” soft, resilient thermoplasticionomer that comprises a melt blend of (a) the acid copolymers or themelt processable ionomers made therefrom as described above and (b) oneor more organic acid(s) or salt(s) thereof, wherein greater than 80%,preferably greater than 90% of all the acid of (a) and of (b) isneutralized. Preferably, 100% of all the acid of (a) and (b) isneutralized by a cation source. Preferably, an amount of cation sourcein excess of the amount required to neutralize 100% of the acid in (a)and (b) is used to neutralize the acid in (a) and (b). Blends with fattyacids or fatty acid salts are preferred.

The organic acids or salts thereof are added in an amount sufficient toenhance the resilience of the copolymer. Preferably, the organic acidsor salts thereof are added in an amount sufficient to substantiallyremove remaining ethylene crystallinity of the copolymer.

Preferably, the organic acids or salts are added in an amount of atleast about 5% (weight basis) of the total amount of copolymer andorganic acid(s). More preferably, the organic acids or salts thereof areadded in an amount of at least about 15%, even more preferably at leastabout 20%. Preferably, the organic acid(s) are added in an amount up toabout 50% (weight basis) based on the total amount of copolymer andorganic acid. More preferably, the organic acids or salts thereof areadded in an amount of up to about 40%, more preferably, up to about 35%.The non-volatile, non-migratory organic acids preferably are one or morealiphatic, mono-functional organic acids or salts thereof as describedbelow, particularly one or more aliphatic, mono-functional, saturated orunsaturated organic acids having less than 36 carbon atoms or salts ofthe organic acids, preferably stearic acid or oleic acid. Fatty acids orfatty acid salts are most preferred.

Processes for fatty acid (salt) modifications are known in the art.Particularly, the modified highly-neutralized soft, resilient acidcopolymer ionomers of this invention can be produced by:

(a) melt-blending (1) ethylene, α,β-ethylenically unsaturated C₃₋₈carboxylic acid copolymer(s) or melt-processible ionomer(s) thereof thathave their crystallinity disrupted by addition of a softening monomer orother means with (2) sufficient non-volatile, non-migratory organicacids to substantially enhance the resilience and to disrupt (preferablyremove) the remaining ethylene crystallinity, and then concurrently orsubsequently

(b) Adding a sufficient amount of a cation source to increase the levelof neutralization of all the acid moieties (including those in the acidcopolymer and in the organic acid if the non-volatile, non-migratoryorganic acid is an organic acid) to the desired level.

The weight ratio of X to Y in the composition is at least about 1:20.Preferably, the weight ratio of X to Y is at least about 1:15, morepreferably, at least about 1:10. Furthermore, the weight ratio of X to Yis up to about 1:1.67, more preferably up to about 1:2. Most preferably,the weight ratio of X to Y in the composition is up to about 1:2.2.

The acid copolymers used in the present invention to make the ionomersare preferably ‘direct’ acid copolymers (containing high levels ofsoftening monomers). As noted above, the copolymers are at leastpartially neutralized, preferably at least about 40% of X in thecomposition is neutralized. More preferably, at least about 55% of X isneutralized. Even more preferably, at least about 70, and mostpreferably, at least about 80% of X is neutralized. In the event thatthe copolymer is highly neutralized (e.g., to at least 45%, preferably50%, 55%, 70%, or 80%, of acid moiety), the MI of the acid copolymershould be sufficiently high so that the resulting neutralized resin hasa measurable MI in accord with ASTM D-1238, condition E, at 190° C.,using a 2160 gram weight. Preferably this resulting MI will be at least0.1, preferably at least 0.5, and more preferably 1.0 or greater.Preferably, for highly neutralized acid copolymer, the MI of the acidcopolymer base resin is at least 20, or at least 40, at least 75, andmore preferably at least 150.

The acid copolymers preferably comprise alpha olefin, particularlyethylene, C₃₋₈. α,β-ethylenically unsaturated carboxylic acid,particularly acrylic and methacrylic acid, and softening monomers,selected from alkyl acrylate, and alkyl methacrylate, wherein the alkylgroups have from 1-8 carbon atoms, copolymers. By “softening,” it ismeant that the crystallinity is disrupted (the polymer is made lesscrystalline). While the alpha olefin can be a C₂-C₄ alpha olefin,ethylene is most preferred for use in the present invention.Accordingly, it is described and illustrated herein in terms of ethyleneas the alpha olefin.

The acid copolymers, when the alpha olefin is ethylene, can be describedas E/X/Y copolymers where E is ethylene, X is the α,β-ethylenicallyunsaturated carboxylic acid, and Y is a softening co-monomer X ispreferably present in 2-30 (preferably 4-20, most preferably 5-15) wt. %of the polymer, and Y is preferably present in 17-40 (preferably 20-40,most preferably 24-35) wt. % of the polymer.

The ethylene-acid copolymers with high levels of acid (X) are difficultto prepare in continuous polymerizers because of monomer-polymer phaseseparation. This difficulty can be avoided however by use of “co-solventtechnology” as described in U.S. Pat. No. 5,028,674, or by employingsomewhat higher pressures than those which copolymers with lower acidcan be prepared.

Specific acid-copolymers include ethylene/(meth) acrylic acid/n-butyl(meth)acrylate, ethylene/(meth) acrylic acid/iso-butyl (meth)acrylate,ethylene/(meth) acrylic acid/methyl (meth)acrylate, and ethylene/(meth)acrylic acid/ethyl (meth)acrylate terpolymers.

The organic acids employed are aliphatic, mono-functional (saturated,unsaturated, or multi-unsaturated) organic acids, particularly thosehaving fewer than 36 carbon atoms. Also salts of these organic acids maybe employed. Fatty acids or fatty acid salts are preferred. The saltsmay be any of a wide variety, particularly including the barium,lithium, sodium, zinc, bismuth, potassium, strontium, magnesium orcalcium salts of the organic acids. Particular organic acids useful inthe present invention include caproic acid, caprylic acid, capric acid,lauric acid, stearic acid, behenic acid, erucic acid, oleic acid, andlinoleic acid.

The optional filler component is chosen to impart additional density toblends of the previously described components, the selection beingdependent upon the different parts (e.g., cover, mantle, core, center,intermediate layers in a multilayered core or ball) and the type of golfball desired (e.g., one-piece, two-piece, three-piece or multiple-pieceball), as will be more fully detailed below.

Generally, the filler will be inorganic having a density greater thanabout 4 grams/cubic centimeter (g/cm³), preferably greater than 5 g/cm³,and will be present in amounts between 0 to about 60 wt. % based on thetotal weight of the composition. Examples of useful fillers include zincoxide, barium sulfate, lead silicate and tungsten carbide, as well asthe other well-known fillers used in golf balls. It is preferred thatthe filler materials be non-reactive or almost non-reactive and notstiffen or raise the compression nor reduce the coefficient ofrestitution significantly.

Additional optional additives useful in the practice of the subjectinvention include acid copolymer wax (e.g., Allied wax AC 143 believedto be an ethylene/16-18% acrylic acid copolymer with a number averagemolecular weight of 2,040), which assist in preventing reaction betweenthe filler materials (e.g., ZnO) and the acid moiety in the ethylenecopolymer. Other optional additives include TiO₂, which is used as awhitening agent; optical brighteners; surfactants; processing aids; etc.

Ionomers may be blended with conventional ionomeric copolymers (di-,ter-, etc.), using well-known techniques, to manipulate productproperties as desired. The blends would still exhibit lower hardness andhigher resilience when compared with blends based on conventionalionomers.

Also, ionomers can be blended with non-ionic thermoplastic resins tomanipulate product properties. The non-ionic thermoplastic resins would,by way of non-limiting illustrative examples, include thermoplasticelastomers, such as polyurethane, poly-ether-ester, poly-amide-ether,polyether-urea, PEBAX® (a family of block copolymers based onpolyether-block-amide, commercially supplied by Atochem),styrene-butadiene-styrene (SBS) block copolymers,styrene(ethylene-butylene)-styrene block copolymers, etc., poly amide(oligomeric and polymeric), polyesters, polyolefins including PE, PP,E/P copolymers, etc., ethylene copolymers with various comonomers, suchas vinyl acetate, (meth)acrylates, (meth)acrylic acid,epoxy-functionalized monomer, CO, etc., functionalized polymers withmaleic anhydride grafting, epoxidization etc., elastomers, such as EPDM,metallocene catalyzed PE and copolymer, ground up powders of thethermoset elastomers, etc. Such thermoplastic blends comprise about 1%to about 99% by weight of a first thermoplastic and about 99% to about1% by weight of a second thermoplastic.

Additionally, the compositions of U.S. Pat. Nos. 6,953,820 and6,653,382, both of which are incorporated herein in their entirety,discuss compositions having high COR when formed into solid spheres.

The thermoplastic composition of this invention comprises a polymerwhich, when formed into a sphere that is 1.50 to 1.54 inches indiameter, has a coefficient of restitution (COR) when measured by firingthe sphere at an initial velocity of 125 ft/s against a steel platepositioned 3 feet from the point where initial velocity and reboundvelocity are determined and by dividing the rebound velocity from theplate by the initial velocity and an Atti compression of no more than100.

The thermoplastic composition of this invention preferably comprises (a)aliphatic, mono-functional organic acid(s) having fewer than 36 carbonatoms; and (b) ethylene, C₃ to C₈ α,β-ethylenically unsaturatedcarboxylic acid copolymer(s) and ionomer(s) thereof, wherein greaterthan 90%, preferably near 100%, and more preferably 100% of all the acidof (a) and (b) are neutralized.

The thermoplastic composition preferably comprises melt-processable,highly-neutralized (greater than 90%, preferably near 100%, and morepreferably 100%) polymer of (1) ethylene, C₃ to C₈ α,β-ethylenicallyunsaturated carboxylic acid copolymers that have their crystallinitydisrupted by addition of a softening monomer or other means such as highacid levels, and (2) non-volatile, non-migratory agents such as organicacids (or salts) selected for their ability to substantially or totallysuppress any remaining ethylene crystallinity. Agents other than organicacids (or salts) may be used.

It has been found that, by modifying an acid copolymer or ionomer with asufficient amount of specific organic acids (or salts thereof); it ispossible to highly neutralize the acid copolymer without losingprocessability or properties such as elongation and toughness. Theorganic acids employed in the present invention are aliphatic,mono-functional, saturated or unsaturated organic acids, particularlythose having fewer than 36 carbon atoms, and particularly those that arenon-volatile and non-migratory and exhibit ionic array plasticizing andethylene crystallinity suppression properties.

With the addition of sufficient organic acid, greater than 90%, nearly100%, and preferably 100% of the acid moieties in the acid copolymerfrom which the ionomer is made can be neutralized without losing theprocessability and properties of elongation and toughness.

The melt-processable, highly-neutralized acid copolymer ionomer can beproduced by the following:

(a) melt-blending (1) ethylene α,β-ethylenically unsaturated C₃₋₈carboxylic acid copolymer(s) or melt-processable ionomer(s) thereof(ionomers that are not neutralized to the level that they have becomeintractable, that is not melt-processable) with (1) one or morealiphatic, mono-functional, saturated or unsaturated organic acidshaving fewer than 36 carbon atoms or salts of the organic acids, andthen concurrently or subsequently

(b) adding a sufficient amount of a cation source to increase the levelof neutralization all the acid moieties (including those in the acidcopolymer and in the organic acid) to greater than 90%, preferably near100%, more preferably to 100%.

Preferably, highly-neutralized thermoplastics of the invention can bemade by:

(a) melt-blending (1) ethylene, α,β-ethylenically unsaturated C₃₋₈carboxylic acid copolymer(s) or melt-processable ionomer(s) thereof thathave their crystallinity disrupted by addition of a softening monomer orother means with (2) sufficient non-volatile, non-migratory agents tosubstantially remove the remaining ethylene crystallinity, and thenconcurrently or subsequently

(b) adding a sufficient amount of a cation source to increase the levelof neutralization all the acid moieties (including those in the acidcopolymer and in the organic acid if the non-volatile, non-migratoryagent is an organic acid) to greater than 90%, preferably near 100%,more preferably to 100%.

The acid copolymers used in the present invention to make the ionomersare preferably ‘direct’ acid copolymers. They are preferably alphaolefin, particularly ethylene, C₃₋₈ α,β-ethylenically unsaturatedcarboxylic acid, particularly acrylic and methacrylic acid, copolymers.They may optionally contain a third softening monomer. By “softening,”it is meant that the crystallinity is disrupted (the polymer is madeless crystalline). Suitable “softening” co-monomers are monomersselected from alkyl acrylate, and alkyl methacrylate, wherein the alkylgroups have from 1-8 carbon atoms.

The acid copolymers, when the alpha olefin is ethylene, can be describedas E/X/Y copolymers where E is ethylene, X is the α,β-ethylenicallyunsaturated carboxylic acid, and Y is a softening comonomer. X ispreferably present in 3-30 (preferably 4-25, most preferably 5-20) wt. %of the polymer, and Y is preferably present in 0-30 (alternatively 3-25or 10-23) wt. % of the polymer. Spheres were prepared using fullyneutralized ionomers A and B as presented in Table I.

TABLE I Cation (% Sample Resin Type (%) Acid Type (%) neut*) M.I. (g/10min) 1A A (60) Oleic (40) Mg (100) 1.0 2B A (60) Oleic (40) Mg (105)*0.9 3C B (60) Oleic (40) Mg (100) 0.9 4D B (60) Oleic (40) Mg (105)* 0.95E B (60) Stearic (40) Mg (100) 0.85 A - ethylene, 14.8% normal butylacrylate, 8.3% acrylic acid B - ethylene, 14.9% normal butyl acrylate,10.1% acrylic acid *indicates that cation was sufficient to neutralize105% of all the acid in the resin and the organic acid.

These compositions were molded into 1.53-inch spheres for which data ispresented in the following table.

TABLE II Sample Atti Compression COR @ 125 ft/s 1A 75 0.826 2B 75 0.8263C 78 0.837 4D 76 0.837 5E 97 0.807

Further testing of commercially available highly neutralized polymersHNP1 and HNP2 had the following properties.

TABLE III Material Properties HNP1 HNP2 Specific Gravity (g/cm³) 0.9660.974 Melt Flow, 190° C., 10-kg load 0.65 1.0 Shore D Flex Bar (40 hr)47.0 46.0 Shore D Flex Bar (2 week) 51.0 48.0 Flex Modulus, psi (40 hr)25,800 16,100 Flex Modulus, psi (2 week) 39,900 21,000 DSC Melting Point(° C.) 61.0 61/101 Moisture (ppm) 1500 4500 Weight % Mg 2.65 2.96

TABLE IV Solid Sphere Data Material HNP1a/HNP2a HNP1 HNP2 HNP2a HNP1a(50:50 blend) Spec. Grav. 0.954 0.959 1.153 1.146 1.148 (g/cm³) FillerNone None Tungsten Tungsten Tungsten Compression 107 83 86 62 72 COR0.827 0.853 0.844 0.806 0.822 Shore D 51 47 49 42 45 Shore C 79 72 75

These materials are exemplary examples of the preferred center and/orcore layer compositions of the present invention. They may also be usedas a cover layer herein.

Golf balls made with such cores enjoy high COR at relatively low clubspeeds. The COR of these balls is higher than the COR of similar ballswith higher compression cores at relatively low club speeds. At higherclub speeds, however, the COR of golf balls with low compression corescan be lower than the COR of balls with higher compression cores. Asillustrated herein, a first golf ball with a 1.505-inch core and a corecompression of 48 (hereinafter “Sample-48”) and a second golf ball witha 1.515-inch core and a core compression of 80 (hereinafter “Sample-80”)were subject to the following distance and COR tests. Sample-48 andSample-80 have essentially the same size core and similar dual-layercover. The single most significant difference between these two balls isthe compression of the respective cores.

TABLE V Ball Speed (ft/s) Average Standard Pro 167 Big Pro 175Compression Driver Driver Driver Driver On Ball Setup Setup Setup SetupSample-48  86 141.7 162.3 167.0 175.2 Sample-80 103 141.5 162.1 168.9176.5 Coefficient of Restitution (COR) 199.8-gram Com- 200-gramCalibration pression Mass Plate Mass Plate Solid Plate Plate On Ball(125 ft/s) (160 ft/s) (160 ft/s) (160 ft/s) Sample-48  86 0.812 0.7640.759 0.818 Sample-80 103 0.796 0.759 0.753 0.836 Difference +0.016+0.005 +0.006 −0.018 (Sample-48 − Sample-80)

As used in the ball speed test, the “average driver set-up” refers to aset of launch conditions, i.e., at a club head speed to which amechanical golf club has been adjusted so as to generate a ball speed ofabout 140 ft/s. Similarly, the “standard driver set-up” refers tosimilar ball speed at launch conditions of about 160 ft/s; the “Pro 167set-up” refers to a ball speed at launch conditions of about 167 ft/s;and the “Big Pro 175 set-up” refers to a ball speed at launch conditionsof about 175 ft/s. Also, as used in the COR test, the mass plate is a45-kilogram plate (100 lbs) against which the balls strike at theindicated speed. The 200-gram solid plate is a smaller mass that theballs strike and resembles the mass of a club head. The 199.8-gramcalibration plate resembles a driver with a flexible face that has a CORof 0.830.

The ball speed test results show that while Sample-48 holds a ball speedadvantage at club speeds of 140 ft/s to 160 ft/s launch conditions,Sample-80 decidedly has better ball speed at 167 ft/s and 175 ft/slaunch conditions.

Similarly, the COR test results show that at the higher collision speed(160 ft/s), the COR generally goes down for both balls, but the199.8-gram calibration test shows that the COR of the higher compressionSample-80 is significantly better than the lower compression Sample-48at the collision speed (160 ft/s). Additionally, while the COR generallygoes down for both balls, the rate of decrease is much less forSample-80 than for Sample-48. Unless specifically noted, COR values usedhereafter are measured by either the mass plate method or the 200-gramsolid plate method, i.e., where the impact plate is not flexible. Unlessotherwise noted, COR values used hereafter are measured by either themass plate method or the 200-gram solid plate method.

The intermediate layers of the present invention may, optionally,comprise a durable, low deformation material such as metal, rigidplastics, or polymers re-enforced with high strength organic orinorganic fillers or fibers, or blends or composites thereof, asdiscussed below. Suitable plastics or polymers include, but not limitedto, high cis- or trans-polybutadiene, one or more of partially or fullyneutralized ionomers including those neutralized by a metal ion sourcewherein the metal ion is the salt of an organic acid, polyolefinsincluding polyethylene, polypropylene, polybutylene and copolymersthereof including polyethylene acrylic acid or methacrylic acidcopolymers, or a terpolymer of ethylene, a softening acrylate classester such as methyl acrylate, n-butyl-acrylate or iso-butyl-acrylate,and a carboxylic acid such as acrylic acid or methacrylic acid (e.g.,terpolymers including polyethylene-methacrylic acid-n or iso-butylacrylate and polyethylene-acrylic acid-methyl acrylate, polyethyleneethyl or methyl acrylate, polyethylene vinyl acetate, polyethyleneglycidyl alkyl acrylates). Suitable polymers also include metallocenecatalyzed polyolefins, polyesters, polyamides, non-ionomericthermoplastic elastomers, copolyether-esters, copolyether-amides, EPR,EPDM, thermoplastic or thermosetting polyurethanes, polyureas,polyurethane ionomers, epoxies, polycarbonates, polybutadiene,polyisoprene, and blends thereof. In the case of metallocenes, thepolymer may be cross-linked with a free radical source, such asperoxide, or by high radiation. Suitable polymeric materials alsoinclude those listed in U.S. Pat. Nos. 6,187,864; 6,232,400; 6,245,862;6,290,611; 6,142,887; 5,902,855; and 5,306,760 and in PCT PublicationNos. WO 01/29129 and WO 00/23519.

Preferably, when the intermediate layer is made with polybutadiene orother synthetic and natural rubber, the rubber composition is highlycross-linked with at least 50 phr of a suitable co-reaction agent, whichincludes a metal salt of diacrylate, dimethacrylate or monomethacrylate. Preferably, the co-reaction agent is zinc diacrylate.Highly cross-linked rubber compounds are discussed in commonly ownedco-pending patent application entitled “Golf Ball and Method forControlling the Spin Rate of Same” bearing application Ser. No.10/178,580 filed on Jul. 20, 2002. This discussion is incorporatedherein by reference.

If desired, the golf ball can include highly rigid materials, such ascertain metals, which include, but are not limited to, tungsten, steel,titanium, chromium, nickel, copper, aluminum, zinc, magnesium, lead,tin, iron, molybdenum and alloys thereof. Suitable highly rigidmaterials include those listed in U.S. Pat. No. 6,244,977. Fillers withvery high specific gravity such as those disclosed in U.S. Pat. No.6,287,217 can also be incorporated into the inner core. Suitable fillersand composites include, but not limited to, carbon including graphite,glass, aramid, polyester, polyethylene, polypropylene, silicon carbide,boron carbide, natural or synthetic silk.

In accordance to one embodiment of the present invention, the golf ballcomprises at least two core layers, an innermost core and an outer core,and a cover. Preferably, outer core comprises a flexible, lowcompression, high COR rubber composition discussed above, and inner corecomprises a low deformation material discussed above. The hard, lowdeformation inner core resists deformation at high club speeds tomaintain the COR at an optimal level, while the resilient outer layerprovides high COR at slower club speeds and the requisite softness forshort iron club play. The inventive ball, therefore, enjoys high initialvelocity and high COR at high and low club head speeds associated, whilemaintaining a desirable soft feel and soft sound for greenside play.

Other rubber compounds for outer core may also include any lowcompression, highly resilient polymers comprising natural rubbers,including cis-polyisoprene, trans-polyisoprene or balata, syntheticrubbers including 1,2-polybutadiene, cis-polybutadiene,trans-polybutadiene, polychloroprene, poly(norbornene), polyoctenamerand polypentenamer among other diene polymers. Outer core may comprise aplurality of layers, e.g., a laminate, where several thin flexiblelayers are plied or otherwise adhered together.

Preferably, the rigid inner core, if present, has a flexural modulus inthe range of about 25,000 psi to about 250,000 psi. More preferably, theflexural modulus of the rigid inner core is in the range of about 75,000psi to about 225,000 psi, and most preferably in the range of about80,000 psi to about 200,000 psi. Furthermore, the rigid inner core hasdurometer hardness in the range of greater than about 70 on the Shore Cscale. The compression of the rigid inner core is preferably in therange of greater than about 60 PGA or Atti. More preferably, thecompression is greater than about 70, and most preferably greater thanabout 80. Shore hardness is measured according to ASTM D-2240-00, andflexural modulus is measured in accordance to ASTM D6272-98 about twoweeks after the test specimen are prepared.

Preferably, the outer core is softer and has a lower compression thanthe inner core. Preferably, outer core has a flexural modulus of about500 psi to about 25,000 psi. More preferably, the flexural modulus isless than about 15,000 psi. The outer core preferably has a hardness ofabout 25 to about 70 on the Shore C scale. More preferably, the hardnessis less than 60 on the Shore C scale.

One preferred way to achieve the difference in hardness between theinner core and the outer core is to make the inner core from un-foamedpolymer, and to make the outer core from foamed polymer selected fromthe suitable materials disclosed herein. Alternatively, the outer coremay be made from these suitable materials having their specific gravityreduced. In this embodiment the inner and outer core can be made fromthe same polymer or polymeric composition.

Preferably, outer core layer has a thickness from about 0.001 inches toabout 0.100 inches, preferably from bout 0.010 inches to about 0.050inches and more preferably from about 0.015 inches to about 0.035inches. Preferably, the overall core diameter is greater than about 1.50inches, preferably greater than about 1.580 inches, and more preferablygreater than about 1.60 inches. The inner core may have any dimension solong as the overall core diameter has the preferred dimensions listedabove.

The cover should be tough, cut-resistant, and selected from conventionalmaterials used as golf ball covers based on the desired performancecharacteristics. The cover may be comprised of one or more layers. Covermaterials such as ionomer resins, blends of ionomer resins,thermoplastic or thermoset urethane, and balata, can be used as known inthe art.

The cover is preferably a resilient, non-reduced specific gravity layer.Suitable materials include any material that allows for tailoring ofball compression, coefficient of restitution, spin rate, etc. and aredisclosed in U.S. Pat. Nos. 6,419,535; 6,152,834; 5,919,100; and5,885,172. Ionomers, ionomer blends, thermosetting or thermoplasticpolyurethanes, metallocenes, polyurethanes, polyureas (and hybridsthereof), are the preferred materials. The cover can be manufactured bya casting method, reaction injection molded, injected or compressionmolded, sprayed or dipped method. Preferably the cover is cast about thecore.

In a preferred embodiment, the golf ball includes an intermediate layer,as either an outer core layer or an inner cover, in addition to theouter cover. As disclosed in the U.S. Pat. Nos. 5,885,172 and 6,132,324,which are incorporated herein by reference in their entireties, outercover layer is made from a soft thermoset material, such as castpolyurethane or polyurea, and inner cover is made from an ionomericmaterial, preferably including at least two ionomers.

When the intermediate layer is an inner cover layer, it is preferablyformed from a high flexural modulus material which contributes to thelow spin, distance characteristics of the presently claimed balls whenthey are struck for long shots (e.g. driver or long irons).Specifically, the inner cover layer materials have a Shore D hardness ofabout 55 or greater, preferably about 55-70 and most preferably about60-70. The flexural modulus of intermediate cover layer is at leastabout 50,000 psi, preferably about 50,000 psi to about 150,000 psi andmost preferably about 75,000 psi to about 125,000 psi. In the preferredembodiment, the intermediate layer has a thickness of from about 0.1inches to about 0.5 inches, more preferably between about 0.11 inchesand about 0.12 inches, and most preferably between about 0.115 inchesand about 0.119 inches. In another thin-layer embodiment, the thicknessof the intermediate layer can range from about 0.020 inches to about0.045 inches, preferably about 0.030 inches to about 0.040 inches andmost preferably about 0.035 inches.

Outer cover layer is formed preferably from a relatively soft thermosetmaterial in order to replicate the soft feel and high spin playcharacteristics of a balata ball for “short game” shots. In particular,the outer cover layer should have Shore D hardness of less than 65 orfrom about 40 to about 64, preferably 40-60 and most preferably 40-50.Additionally, the materials of the outer cover layer must have a degreeof abrasion resistance in order to be suitable for use as a golf ballcover. The outer cover layer of the present invention can comprise anysuitable thermoset or thermoplastic material, preferably which is formedfrom a castable reactive liquid material. The preferred materials forthe outer cover layer include, but are not limited to, thermoseturethanes and polyurethanes, thermoset urethane ionomers and thermoseturethane epoxies. Examples of suitable polyurethane ionomers aredisclosed in U.S. Pat. No. 5,692,974 entitled “Golf Ball Covers,” thedisclosure of which is hereby incorporated by reference in its entiretyin the present application. Thermoset polyurethanes and polyureas arepreferred for the outer cover layers of the balls of the presentinvention.

In accordance with another embodiment of the present invention, the golfball comprises a relatively small, low compression, high COR inner core.The diameter of the inner core (or center) is preferably less than 1.40inches or smaller, more preferably 0.8 inches to about 1.4 inches, andmost preferably from about 1.3 inches to about 1.4 inches. The desiredthickness of either the core (center) or intermediate layer can beselected in conjunction with the flexural modulus of the material of thelayers and the desired overall compression of the ball and deformationof the ball.

Most preferably, inner core is formed from a rubber compositioncontaining a halogenated thiophenol compound. Such halogenatedthiophenol compounds are fully disclosed in commonly owned andco-pending '963 and '448 patent applications, which have alreadyincorporated by reference and discussed above. In accordance to oneaspect of the second embodiment, the rubber compound preferably is ahigh cis- or trans-polybutadiene and has a viscosity of about 40 Mooneyto about 60 Mooney. The core has a hardness of greater than about 70 onthe Shore C scale, and preferably greater than 80 on the Shore C scale.The core also has a compression of less than about 60 PGA, and morepreferably less than about 50 PGA. The resulting core exhibits a COR ofat least about 0.790, and most preferably at least 0.800 at 125 ft/s.Other suitable polymers for inner core include a polyethylene copolymer,EPR, EPDM, a metallocene catalyzed polymer or any of the materialsdiscussed above in connection with outer core discussed above, so longas the preferred compression, hardness and COR are met.

Inner core may be encased by outer core layers comprising the samematerials or different compositions than inner core. These outer corelayers may be laminated together. Each of the laminate layers preferablyhas a thickness from about 0.001 inches to about 0.100 inches and morepreferably from about 0.010 inches to about 0.050 inches.

Preferably, the intermediate layer is made from a low deformationpolymeric material, such as an ionomer, including low and high acidionomer, any partially or fully neutralized ionomer or any thermoplasticor thermosetting polymer. The intermediate layer preferably has aflexural modulus of greater than 50,000 psi and more preferably greaterthan 75,000 psi. Among the preferred materials are hard, high flexuralmodulus ionomer resins and blends thereof. Additionally, other suitablemantle materials (as well as core and cover materials) are disclosed inU.S. Pat. No. 5,919,100 and international publications WO 00/23519 andWO 01/29129. These disclosures are incorporated by reference herein intheir entireties. One particularly suitable material disclosed in WO01/29129 is a melt processable composition comprising a highlyneutralized ethylene copolymer and one or more aliphatic,mono-functional organic acids having fewer than 36 carbon atoms of saltsthereof, wherein greater than 90% of all the acid of the ethylenecopolymer is neutralized.

These ionomers are obtained by providing a cross metallic bond topolymers of monoolefin with at least one member selected from the groupconsisting of unsaturated mono- or di-carboxylic acids having 3 to 12carbon atoms and esters thereof (the polymer contains 1 to 50% by weightof the unsaturated mono- or di-carboxylic acid and/or ester thereof).More particularly, such acid-containing ethylene copolymer ionomercomponent includes E/X/Y copolymers where E is ethylene, X is asoftening comonomer such as acrylate or methacrylate present in 0-50weight percent of the polymer (preferably 0-25 wt. %, most preferably0-20 wt. %), and Y is acrylic or methacrylic acid present in 5-35 weightpercent of the polymer (preferably at least about 16 wt. %, morepreferably at least about 16-35 16 wt. %, most preferably at least about16-20 16 wt. %), wherein the acid moiety is neutralized 1-90%(preferably at least 40%, most preferably at least about 60%) to form anionomer by a cation such as lithium*, sodium*, potassium, magnesium*,calcium, barium, lead, tin, zinc* or aluminum (*=preferred), or acombination of such cations. Specific acid-containing ethylenecopolymers include ethylene/acrylic acid, ethylene/methacrylic acid,ethylene/acrylic acid/n-butyl acrylate, ethylene/methacrylicacid/n-butyl acrylate, ethylene/methacrylic acid/iso-butyl acrylate,ethylene/acrylic acid/iso-butyl acrylate, ethylene/methacrylicacid/n-butyl methacrylate, ethylene/acrylic acid/methyl methacrylate,ethylene/acrylic acid/methyl acrylate, ethylene/methacrylic acid/methylacrylate, ethylene/methacrylic acid/methyl methacrylate, andethylene/acrylic acid/n-butyl methacrylate. Preferred acid containingethylene copolymers include ethylene/methacrylic acid, ethylene/acrylicacid, ethylene/methacrylic acid/n-butyl acrylate, ethylene/acrylicacid/n-butyl acrylate, ethylene/methacrylic acid/methyl acrylate andethylene/acrylic acid/methyl acrylate copolymers. The most preferredacid-containing ethylene copolymers are ethylene/methacrylic acid,ethylene/acrylic acid, ethylene/(meth)acrylic acid/n-butyl acrylate,ethylene/(meth)acrylic acid/ethyl acrylate, and ethylene/(meth)acrylicacid/methyl acrylate copolymers.

The manner in which the ionomers are made is well known in the art asdescribed in e.g., U.S. Pat. No. 3,262,272. Such ionomer resins arecommercially available from DuPont under the tradename SURLYN® and fromExxon under the tradename IOTEK®. Some particularly suitable SURLYNS®include SURLYN® 8140 (Na) and SURLYN® 8546 (Li), which have amethacrylic acid content of about 19%.

Other suitable mantle materials include the low deformation materialsdescribed above and any hard, high flexural modulus, resilient materialthat is compatible with the other materials of the golf ball. Examplesof other suitable inner cover materials include thermoplastic orthermoset polyurethanes, thermoplastic or thermoset polyetheresters orpolyetheramides, thermoplastic or thermoset polyester, a dynamicallyvulcanized elastomer, a functionalized styrenebutadiene elastomer, ametallocene polymer or blends thereof.

Suitable thermoplastic polyetheresters include materials, which arecommercially available from DuPont under the tradename HYTREL®. Suitablethermoplastic polyetheramides include materials, which are availablefrom Elf-Atochem under the tradename PEBAX®. Other suitable materialsfor the inner cover layer include nylon andacrylonitrile-butadiene-styrene copolymer (ABS).

Another suitable material for the intermediate layer is a highstiffness, highly neutralized ionomer having a durometer hardness of atleast about 50 on the Shore D scale and a flexural modulus of at least50,000 psi. The flexural modulus ranges from about 50,000 psi to about150,000 psi. The hardness ranges from about 55 to about 80 Shore D, morepreferably about 55 to about 70 Shore D. This ionomer, preferably atleast two ionomers, may be blended with a lowly neutralized ionomershaving an acid content of 5 to 25%, and may be blended withnon-ionomeric polymers or compatilizers (e.g., glycidyl or maleicanhydride), so long as the preferred hardness and flexural modulus aresatisfied. Examples of highly neutralized ionomers are disclosed in U.S.Pat. No. 6,756,436 which is incorporated herein by reference.

In one preferred embodiment, this suitable material is a blend of afatty acid salt highly neutralized polymer, such as a melt processablecomposition comprising a highly neutralized ethylene copolymer and oneor more aliphatic, mono-functional organic acids having fewer than 36carbon atoms of salts thereof, wherein greater than 90% of all the acidof the ethylene copolymer is neutralized, and a high stiffness partiallyneutralized ionomer, such as those commercially available as SURLYN®8945, 7940, 8140 and 9120, among others. This blend has hardness in therange of about 65 to about 75 on the Shore D scale.

The intermediate layer may also comprise a laminated layer, if desired.For example, the intermediate layer may comprise a laminate comprisingfour layers: a polyamide layer having a flexural modulus of about200,000 psi, a terpolymer ionomer or un-neutralized acid terpolymerhaving a flexural modulus of about 30,000 psi, a low acid ionomer havinga flexural modulus of about 60,000 psi and a high acid ionomer having aflexural modulus of about 70,000 psi. The composite flexural modulus ofthe four-layer laminate is about 90,000 psi or approximately the averageof the flexural modulus of the four layers, assuming that the thicknessof each layer is about the same.

In a preferred embodiment, inner core, if present, has a diameter ofabout 0.800 to about 1.400 inches, more preferably about 1.3 to about1.4 inches, a compression of about 44 or less, and a COR of about 0.800.The intermediate layer comprises at least two ionomers having a flexuralmodulus of about 50,000 psi or higher and has a thickness of at leastabout 0.110 inches, preferably between about 0.11 inches and about 0.12inches. The cover is preferably a cast polyurethane or polyurea having ahardness of about 40 to about 60 Shore D. The core compression ispreferably about 44 or less, and the combination of core andintermediate layer has a compression of from about 70 to about 100.

The core preferably comprises a single solid layer. Alternatively, thecore may comprise multiple layers. Preferably, its diameter is about1.400 inches or less, more preferably between about 0.8 inches and about1.4 inches, most preferably between about 1.3 inches and about 1.4inches. The core has a COR of about 0.770 or greater, more preferablyabout 0.800 or greater, and most preferably about 0.820 or greater, soas to give the ball a COR of at least 0.800 and more preferably in therange of about 0.805 to about 0.820. In one preferred embodiment, thecore has a COR of about 0.770 to about 0.810.

In a preferred embodiment, intermediate cover layer and outer coverlayer are similar to the inner cover layer and the outer cover layer ofcover, respectively, for progressive performance. For example, outercover layer is made from a soft, thermosetting polymer, such as castpolyurethane, and intermediate cover layer is made from a rigid ionomeror similar composition having hardness of at least 55 on the Shore Dscale and flexural modulus of at least 55,000 psi.

The total thickness the cover is preferably less than 0.125 inches.Innermost layer preferably is about 0.005 inches to about 0.100 inchesthick, more preferably 0.010 inches to about 0.090 inches, and mostpreferably about 0.015 inches to about 0.070 inches. Intermediate coverlayer preferably is about 0.010 inches to about 0.050 inches thick, andouter cover layer preferably is about 0.020 inches to about 0.040 inchesthick.

Golf balls made in accordance to the present invention and disclosedabove have a compression of greater than about 60 PGA, more preferablygreater than about 80 and even more preferably greater than about 90PGA. These balls exhibit COR of at least 0.80 at 125 ft/s and morepreferably at least 0.81 at 125 ft/s. These balls also exhibit COR of atleast 0.75 at 160 ft/s and more preferably at least 0.76 at 160 ft/s.

All patents and patent applications cited in the foregoing text areexpressly incorporated herein by reference in their entirety.

The invention described and claimed herein is not to be limited in scopeby the specific embodiments herein disclosed, since these embodimentsare intended as illustrations of several aspects of the invention. Anyequivalent embodiments are intended to be within the scope of thisinvention. Indeed, various modifications of the invention in addition tothose shown and described herein will become apparent to those skilledin the art from the foregoing description. Such modifications are alsointended to fall within the scope of the appended claims.

1. A golf ball comprising: a core comprising a center and an outer corelayer comprising polyoctenamer, the core having a compression of 70 orless, an outer diameter of about 1.38 inches to 1.387 inches, and acoefficient of restitution of about 0.770 to 0.810; a cover comprisingan inner cover layer and an outer cover layer, the outer cover layerhaving a thickness of about 0.02 inches to 0.04 inches and comprising acastable polyurethane having a hardness of about 40 to 60 Shore D; andan intermediate layer disposed between the core and the cover, theintermediate layer having a thickness of about 0.015 inches to 0.07inches, a hardness of about 55 Shore D to 70 Shore D, and comprising ahighly-neutralized ionomer; wherein a combination of the core and theintermediate layer has a compression of about 60 or greater and the golfball has a coefficient of restitution of 0.805 or greater when measuredat an incoming velocity of 125 ft/s.